Female locking plugs for extension cords are well known in the art; see, for example, U.S. Pat. Nos. 3,710,304; 4,133,919; and 5,352,132. In these prior art references, a female locking plug incorporates a pair of release buttons or unlocking pins that fit into the apertures of a standard male plug. However, it would be difficult to manufacture the standard type of wall receptacles using such a pair of release buttons or locking pins.
A spring locking mechanism has been designed that incorporates a spring between a pair of steel balls that move within apertures of a standard male plug to assure that a good electrical connection is made between the male plug and the female receptacle; see U.S. Pat. No. 2,198,504. However, the prior art spring locking mechanism does not use any release buttons or unlocking pins. The user simply uses sufficient force to overcome the compressive force of the spring to disconnect the male plug from the female outlet. This mechanism is not considered to be a female locking outlet of the type described above.
There is a need for a female locking electrical outlet using the same locking mechanism on extension cords as well as wall receptacles and one that can accept a plurality of male electrical plugs. There is also a need for a less complex and easier to manufacture female locking electrical outlet than those of the prior art.